论文标题
$ 1 \ textIt {t} - {\ mathrm {tise}} _ {2} $的戏剧性等离子体响应对电荷密度 - 波差距开发的响应
Dramatic Plasmon Response to the Charge-Density-Wave Gap Development in $1\textit{T}-{\mathrm{TiSe}}_{2}$
论文作者
论文摘要
1T-TISE2是研究最多的电荷密度波（CDW）系统之一，不仅是因为其与CDW过渡相关的特性，而且还因为它是由CDW波载体上提议的等离子体软化信号的有前途的激子绝缘子候选者。使用高分辨率电子损失光谱法，我们报告了对1T-Tise2温度依赖性等离子体行为的系统研究。我们明确地从声子模式中解析了等离子体，从有限动量下揭示了Landau在有限动量下对等离子体的存在，这不支持等离子体缩合的等离子体软化图片。此外，我们发现，零动量的等离子体寿命对与CDW过渡相关的带隙进化做出了巨大反应。在正常相中，Fermi能量附近的带间过渡被证明是等离子的强阻尼通道，而CDW相中的这种通道由于CDW间隙的开口而受到抑制，这导致了在半算法或小间隙半导体中等离子体的可调性。
1T-TiSe2 is one of the most studied charge density wave (CDW) systems, not only because of its peculiar properties related to the CDW transition, but also due to its status as a promising candidate of exciton insulator signaled by the proposed plasmon softening at the CDW wave vector. Using high-resolution electron energy loss spectroscopy, we report a systematic study of the temperature-dependent plasmon behaviors of 1T-TiSe2. We unambiguously resolve the plasmon from phonon modes, revealing the existence of Landau damping to the plasmon at finite momentums, which does not support the plasmon softening picture for exciton condensation. Moreover, we discover that the plasmon lifetime at zero momentum responds dramatically to the bandgap evolution associated with the CDW transition. The interband transitions near the Fermi energy in the normal phase is demonstrated serving as a strong damping channel of plasmons, while such a channel in the CDW phase is suppressed due to the CDW gap opening, which results in the dramatic tunability of the plasmon in semimetals or small-gap semiconductors.
